Threaded Ring Gauge Long Form Calibration Certificate No Material Tool Steel Dimension Type Metric Gauge Type Go (Plus) Pitch Diameter 18.334 mm Pitch Diameter - Go Member 18.334 mm Thread Class 6G Thread Length 19 mm Thread Size M20 x 2.50 Thread Type Metric Compatible Holder Size 4T Finish Uncoated Gauge Design Adjustable Hardness RC 60-62 Included Certification Certificate of Accuracy with NIST Traceability Standards ASME B1.16M Tolerance Class X